We proposed a novel design of irrigated wet brush ablation electrode that is flexible and efficiently cooled for RF catheter ablation. We described the FEM method to analyze lesion and temperature distribution during ablation. The analysis demonstrated that this brush electrode is capable of creating lesions up to 10 mm deep. The ablation electrode is maintained at lower temperature by the irrigation and lesion is much deeper than non-irrigated ablation electrode. The results also suggested that the electrical conductivity of the material is more critical than thermal conductivity to lesion creation. The optimal electrical conductivity for the brush material should larger than 1 mS/mm.